This application claims the priority of German Application No. 197 23 521.2, filed Jun. 5, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process for providing outside temperature information for the outside-temperature-dependent air conditioning of a motor vehicle interior, in which the outside temperature is continuously sensed and the outside temperature information, which influences the air conditioning, is obtained from the pertaining sensor signal. During hold phases, which are triggered with the occurrence of a defined starting position, the outside temperature information which influences the air condition is held at its temperature value in the event of a rising or unchanged sensed outside temperature value.
This type of a process is described in German Patent Document DE 42 06 013 C1. In that process, the outside temperature is sensed continuously, that is, in a timed manner at given time intervals, and from it, the outside temperature is obtained as a considerably damped sensor signal value in that the pertaining sensor signal is first subjected to a weak first damping and the weakly damped signal is then subjected to a strong second damping. During the hold phases, the outside temperature information which influences the air conditioning, despite a rising sensed outside temperature value, is not increased correspondingly but is held in this situation at its momentary temperature value. As a starting condition for the triggering of such hold phases, the selected condition there is that the vehicle speed fall below a definable speed threshold value of, for example, 30 km/h. This has the purpose of preventing, shortly after the parking of the vehicle, the outside temperature sensor signal from being used as the relevant outside temperature information for the air conditioning of the vehicle interior, which is then considerably influenced by the waste heat of the vehicle, for example, by the still hot vehicle engine, and therefore does not reflect the true outside temperature value. As a further measure, starting values as a function of the engine cooling water temperature are used during the starting of the vehicle as the basis of the weakly damped outside temperature value and the strongly damped outside temperature value. If the cooling water temperature is higher than a definable threshold value of, for example, 40.degree. C., both damped outside temperature values are set to the stored, strongly damped outside temperature value existing at the time of the previous parking of the vehicle, whereas, if the cooling water temperature is lower or equal to the pertaining threshold value, both are set to the outside temperature value sensed at the point in time of the starting of the vehicle.
One problem of the known process consists of the fact that, whenever the vehicle is started in a colder environment, for example, in an underground garage, and is then driven at a low vehicle speed, which remains under the speed threshold value, into a warmer environment, for example, in the stop-and-go traffic outside the underground garage, the outside temperature information used for the air conditioning of the vehicle interior is held at the initial cooler temperature value although the vehicle is already situated in a clearly warmer outside environment.
The invention is based on the technical problem of providing a process of the above-mentioned type by which outside temperature information is provided for the air conditioning of the vehicle interior which takes place as a function of the outside temperature and is very appropriate for the respective situation.
The invention solves this problem by providing a process for providing outside temperature information for an outside-temperature-dependent air conditioning of a motor vehicle interior. The outside temperature is continuously sensed and, from the pertaining sensor signal, the air-conditioning-influencing outside temperature information (T.sub.B) is obtained. During hold phases which are triggered when a defined starting condition occurs, the air-conditioning-influencing outside temperature information is held at its temperature value when the sensed outside temperature value rises or stays the same. The hold phase starting condition consists of the fact that the vehicle speed (v) is lower than a definable speed threshold value (v.sub.S) and the temperature (T.sub.K) of the motor vehicle driving engine or of a coolant for this driving engine is higher than a definable engine temperature threshold value or coolant temperature threshold value (T.sub.KS).
In this process, the holding of the air-conditioning-influencing outside temperature information in the event of a rising or unchanging sensed outside temperature value, is in each case triggered only when not only the vehicle speed is lower than a definable speed threshold value but, in addition, the temperature of the motor vehicle driving engine or of its coolant is higher than a definable engine temperature threshold value or coolant temperature threshold value. By holding the air-conditioning-influencing outside temperature information constant at a low vehicle speed and when the engine temperature or coolant temperature is above the respective threshold value, it is prevented that, during a vehicle start, after only a brief stoppage, a sensed outside temperature value which is rising because of the still existing vehicle waste heat and is therefore falsified is used as the air-conditioning-influencing outside temperature information. On the other hand, this holding of the air-conditioning-influencing outside temperature information does not take place when the vehicle driving engine is not yet warm so that a rise of the sensed outside temperature value, which in this case is based on an actual increase of the outside temperature, is taken into account for the air conditioning of the vehicle interior. In particular, when driving out of a cooler underground garage with a still cold engine into the warmer outside environment, this rise of the outside temperature can immediately be taken into account for the air conditioning of the vehicle interior even if the vehicle is being driven very slowly at the time.
The selection of the engine temperature threshold value or coolant threshold value in the range of between approximately 55.degree. C. and approximately 65.degree. C. was found to be advantageous.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.